Abstract: Gushan Iron Mine of MaSteel Group is in typical complex geological circumstances of igneous rock and the traditional support can't meet with the requirement on tunnel stability. In order to adopt a reasonable excavation and support scheme, research was made for the N14 tunnel conjunction which is near to the south working face at the shaft bottom of -300 m level of Hou Hemuhan mine section. It is decided to adopt the pilot tunnel method for the excavation. According to the site geological characteristic and the support mechanism of bolting-shotcreting, bolting-grouting and pre-stressed anchor cable, it is decided to adopt a combined support scheme consisting of bolting-shotcreting for the primary flexible support and bolting-grouting and pre-stressed anchor cable for the secondary strengthening support, which has achieved good technical effect and economical benefit. The results show that the flexible stress-release support should be timely executed for the construction at the conjunction with great disturbance, the fractured and dilatable surrounding rock be rapidly sealed, and the support method combining bolting-grouting and pre-stressed anchor cable be used for large cross-sectional tunnel or the surrounding rock in large loose zone.

Key words: Tunnel, Conjunction, Pilot tunnel, Bolting-grouting support